This invention relates to methods and construction of a castable unit of footwear. It relates particularly to a method of making a customized, form-fitted footwear casting unit for engagement with and support of the undersurface of a person's foot in the footwear.
Current footwear has little to do with the inherent natural characteristics of the human foot in a comfortable and natural state. The flat, hard, innersoles of most of today's footwear only accentuate the concrete and pavement society in which we live and work. The usual footwear forces the foot into rigid and unnatural positions which cause discomfort to the wearer and which also can cause deformities to the feet.
It is well recognized that if the shoe fits the foot well, then it will be more comfortable to wear. And the comfort of one's feet has a great deal of effect upon one's emotional and physical states.
A large number of different techniques have been tried to improve the fit of a shoe. Resilient inner soles and inserts which provide support for the arches are often used to relieve some of the discomfort resulting from the flat, hard inner soles. Precontoured innersoles, such as preshaped wooden sandals, have also been used. And attempts have been made to provide a more customized fit by the use of molds. See for example, U.S. Pat. No. 2,742,717 issued Apr. 24, 1956 to Allen E. Murray which describes a method of hand forming a felt platform to a person's foot.
Athletic footwear presents its own special problems. In ski boots, for example, it is quite desirable to obtain a foot to boot fit that minimizes lost motion or slack between the foot and the ski. U.S. Pat. No. 3,581,412 issued June 1, 1971 to Melvin W. Dalebout discloses a technique of snuggly fitting a ski boot to the foot while cushioning the foot from the relative hard and rigid outer shell of the boot. In this patent an inner liner or boot is positioned within an outer shell with a cavity surrounding the inner boot. The user slips his foot in the inner liner and a liquid resin elastomer reaction mixture is then injected into the cavity and entirely around the bottom, sides and top of the foot and lower ankle. This reaction mixture is then permitted to set up to provide a snug fit about the entire foot and lower ankle of the person wearing the boot. Since the primary purpose in the U.S. Pat. No. 3,581,412 patent is to provide a snug fitting ski boot for stabilizing the position of the foot with respect to the ski, rather than providing a customized fit and support of the underside of the foot, no attempt is made to custom shape the innersole surface by stepping down on the boot to apply the person' s weight to the foot within the boot while the reaction mixture is setting up. Instead, as pointed out at column 4, lines 16 through 24 of this patent, an enlarged toe area is obtained by using an appropriately sized covering over the toes before the individual's foot is placed in the boot to thereby provide an enlarged compartment for the toes.
The prior art therefore has not provided a practical method or construction for obtaining a completely customized fit between the innersole and the foot in footwear.
It is a primary object of the present invention to overcome this deficiency of the prior art. It is a closely related object to provide a customized fit of the sole in footwear of the kind used for ordinary every day use.